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THREE PHASE POWER & SINGLE PHASE POWER
3 phase power is typically 150% more efficient than single phase in the same power range. In a single phase unit the power falls to zero three times during each cycle, in 3 phase it never drops to zero. The power delivered to the load is the same at any instant.

If you have an 80% efficient single phase motor, there is no way that you will be able to replace it with a three phase motor that is 150% more efficient.

-Jon